'Grey's Anatomy's Kelly McCreary: There's a Lot Maggie Doesn't Know

ABC/Adam Taylor

The actress talks to THR about how Meredith and Richard will respond to their new relative and whether Maggie knows about Ellis' Alzheimer's and more

Maggie Pierce (Kelly McCreary) may have arrived at Grey Sloan to find out more about her biological mother, but she's going to get more than she could ever bargain for this season on ABC's Grey's Anatomy.

After arriving as a new cardio doc to fill the void created by Cristina's (Sandra Oh) departure, the new doc has clashed with half-sister Meredith (Ellen Pompeo) and hit it off with Richard (James Pickens Jr.), whom she has no idea is her biological father.

The Hollywood Reporter caught up with McCreary to discuss friction with Mer, how Richard could respond and just how much she knows about her biological mother.

Maggie hasn't had an easy road joining the ranks at Grey Sloan. How has your personal experience been by comparison?

It's been so much better than Maggie's! One of the great things about Grey's is that it is a well-oiled machine. People have their routine; things run smoothly and questions get answered easily. It's a really chill working environment. And because it has been around for 10 years, everybody is curious and excited about who Maggie is and how she's going to affect each of the other characters.

Were you a big Grey's fan before you were cast? Did you know you'd be playing Mer's sister?

When I got the job, I didn't know who I was playing. I found out an hour before the season 10 finale table read. When the reveal happened during the table read, the room erupted. Everybody was freaking out about the existence of this character. That's when I first started to get really excited about the possibilities of this character. I had watched Grey's devotedly the first couple of years and picked it up again this summer after I got the job. After I finished watching the most recent seasons, I started from beginning. It's really fun to watch and realize what a great legacy I get to be a part of.

How will Meredith and Maggie's relationship evolve? Will their story be different than Mer and Lexie?

It's different then Lexie (Chyler Leigh) and Meredith because Maggie is actually the head of the department; she outranks Meredith in a way, professionally speaking. Meredith has seniority and she's on the board of the hospital, but it's a different power dynamic in terms of status in the hospital, than Maggie and Lexie. Maggie also won't really back down from a fight; she's very decisive — and so is Meredith. They are both strong willed, and that is a dynamic that will be very interesting to watch play out.

Will the fact that Ellis (Kate Burton) has two daughters somewhat diminish the pressure of wanting to follow in her legacy, or do you think that's only going to amplify the competition between Meredith and Maggie?

I don't think of their relationship as competitive. Maggie is extremely accomplished in her own way. She is a 31-year-old head of cardiothoracic surgery. She's as ambitious as Ellis was, and will be as accomplished. What that does to ignite the fire under Meredith? I bet it will, especially given Cristina's line, "He is not the sun, you are," and Meredith's realization at the end of last season that she has put her career in second position. So she's already primed for that.

Secrets in Shondaland don't last long. What could you say about how Meredith could respond when and if she eventually finds out that they're half-sisters?

From Thatcher (Jeff Perry) and his family to Lexie, Maggie is the latest family member of Meredith's to come out of the wood work and things have never gone well. Eventually Lexie and Meredith came to love and appreciate each other, but it didn't get off to a great start. If the audience were to infer that Meredith is not going to be happy about Maggie, then based on the past, they wouldn't be too far off the mark (laughs).

How much of Maggie's backstory and what her life was like prior to Grey Sloan can we expect to learn this season?

We're going to learn a lot about her parents. We're going to see her dynamic with her parents in the next episode. They will appear but they make their presence known in some pretty comical, sweet ways. So far, that's pretty much it that I know of. We will definitely get to know about the depth and richness of her relationship with her parents.

How much does Maggie knows about Ellis? Is she aware of Ellis' battle with Alzheimer's? Is that a fear as real for her as it is for Meredith?

She doesn't know how anything other then that she is a very accomplished doctor and surgeon. There's a whole can of worms to be opened up for her. Maggie doesn't know that Ellis was not the warmest, healthiest mother. There's a whole Pandora's box worth of stuff to find out that Maggie knows nothing about.

Richard seems to know that he is Maggie's biological dad. At some point might someone let that slip?I think he does know. No one else knows except for Amilia (Caterina Scorsone), but it's possible.

How do you think Maggie will respond to learning that Richard is her father?

Maggie is here looking for information about her family, so it could go a number of ways. It could be awesome that she has found a little gem that she didn't even come from Boston to Seattle to pursue. She doesn't have any leads at all on her father, it could go that way, or she could not be thrilled with the way Richard handled the information. We'll just have to wait and see.

What are you looking forward to learning about Maggie? Hit the comments with your thoughts. Grey's Anatomy airs on Thursdays at 8 p.m. on ABC.